Manchester United are close to completing what is technically their third signing of the summer as teenage sensation Chido Obi-Martin is set for Old Trafford. The 16-year-old striker rejected Arsenal’s offer of professional terms to sign for United in a huge statement of intent by the club. While he is not expected to join the first team straight away, it would be a major surprise if he didn’t end this season with a senior appearance or two. Obi-Martin comes highly rated, as his goals plundering at the youth level was borderline stuff of legends. Now, Amad might just have revealed why the prod…